Here, \(C_{t,T,F}\)  is the constant of the trace inequality \(\Vert v-\overline{v}_F\Vert _F \le C_{t,T,F} h_F^{{1}{2}} \Vert \nabla v\Vert _T\)  with \(\overline{v}_F\frac{1}{|F|}\int _Fv\)  valid for every \(v\in H^1(T)\)  and \(F\in \mathcal {F}_T\) ; see [1]} or [2]}.
